In vehicles such as automobiles, conventionally, attempts to dispose various vibration isolators at those parts probably serving as sources of vibrations or noises and thereby to restrain the vibrations or noises from penetrating into the vehicle compartment have been made, in order to enhance comfort of the passengers. For example, in relation to an engine which is a main source of vibrations and noises, vibration isolating rubbers have been used for such component members as the torsional damper and the engine mount, to thereby absorb the vibrations during driving of the engine and to restrain both penetration of vibrations or noises into the compartment and diffusion of the noises to the peripheral environments.
As fundamental properties, such a vibration isolating rubber is required to have a strength characteristic for supporting a heavyweight body such as the engine and a vibration isolating performance for absorbing and suppressing vibrations. Further, a vibration isolating rubber for use in a high-temperature environment such as an engine room is required to have not only a low dynamic-to-static modulus ratio and an excellent vibration isolating performance but also high thermal resistance and durability. Especially, in recent years, the temperature inside the engine room has been tending to rise, attendant on a rise in engine output and a saving of engine room space for securing a wider compartment space. This tendency urges the vibration isolating rubber to be more often used in severer environments. Consequently, the vibration isolating rubbers for automotive use have come to be desired to meet severer requirements in regard of thermal resistance and the like.
An art in which silica gel is blended into a base rubber, in order to attain both a low dynamic-to-static modulus ratio and good thermal resistance, has been proposed in JP-A 2006-131871 (Patent Document 1). In addition, an art in which a high-structure carbon having a large particle diameter is blended into a base rubber, in order to achieve both a low dynamic-to-static modulus ratio and good thermal resistance, has been proposed in JP-A 2006-143859 (Patent Document 2). In general, however, the relationship between a low dynamic-to-static modulus ratio and good thermal resistance as well as the relationship between a low dynamic-to-static modulus ratio and good durability is an antinomic relationship. Besides, it is desired to achieve a lowering in dynamic-to-static modulus ratio and enhancement of durability on a still higher level as compared with the above-mentioned related arts.